1. Field of the Invention
The present invention relates to an LC type plug with a shutter used for a connecting end of an optical fiber cable.
2. Prior Art
In the prior art, as a known LC type plug, there is an LC type plug 15 including a cylindrical plug frame 18 having a ferrule 16 and a spring 17 configured to bias the ferrule 16 forward in the interior thereof; a cylindrical front housing (movable) 19 surrounding an outside of the plug frame 18 in sliding contact therewith; an elongated spring 21 obtaining a reaction force from a locking housing 20 so as to always bias the front housing (movable) 19 forward; a light-shielding plate (shutter) 22 having a curved shape, fixed at one end portion thereof to a front inner wall of the front housing 19, and configured to block light at a position in front of the ferrule 16; and the locking housing 20 configured to be fitted from the rear of the plug frame 18 as illustrated in FIG. 9A to FIG. 13.
In the LC type plug 15, the front housing 19 is biased forward by the spring 21 in a non-connected state so that the light-shielding plate 22 fixed to the front housing 19 protects eyes or the like by blocking laser beams from the ferrule 16, and the light-shielding plate 22 comes into abutment with an opening of the plug frame 18 by the retracted front housing 19 against a biasing force of the spring 21 in a connected state to extend the light-shielding plate 22 from the curved shape to a straight shape. Accordingly, the ferrule 16 protrudes from an opening end portion of the front housing 19 moved rearward, and the ferrule 16 on the LC type plug 15 side and a ferrule of an LC type adapter 24 as a connection counterpart (see FIGS. 2A and 2B) are connected (see JP-A-2011-13606).
However, in the LC type plug 15 with a shutter of the prior art, part of the elongated spring 21 that biases the front housing 19 always forward is exposed to the outside except for both end portions thereof as illustrated in FIG. 12. Therefore, there are probabilities of breakage during operation and corrosion after a long time of use. In addition, there is a problem that the number of components is increased and the number of assembly steps is also increased due to the usage of a pin 21a for preventing buckling of the elongated spring 21. The LC type plug with a shutter of the invention is proposed for solving the above-described problems.